The Plan of Saint Gall is the oldest known medieval architectural drawing. Dating from the early 9th c., it depicts of a monastic compound. The plan itself was never realised to full extend in its time. In the present, a society called "karolingische klosterstadt e.V." is trying to build the plan in full scale at "Campus Galli" near Lake Constance, applying methods and tools of the Early Middle Ages. The article deals with the impact of such an enterprise in terms of living history and discusses a concept to train the labourers and craftsmen as costumed interpreters.